Photoactivation of aminotriarylmethane dye cyanides



-waxes, are insoluble in water. systems are especially useful with the rosaniline series.

BHOTOACTIVATION on AMINOTRIARYLMETH- ANE DYE CYANIDES Lyman Chalkley, Prince Georges County, Md.

19 Claims. (Cl. 96-85) This invention relates to a photochemical process and product, and more particularly to the photoactivation of the cyanides :of the aminotriarylmethane dyes. In my US. Patent 2,676,887 there is a general discussion of the role of photoactivators in the photolysis of dye cyanides and a disclosure of five classes of photoactivator materials. T he present invention is based upon the discovery of a new class of photoactivator materials, namely the carboxylic acid amides.

The cyanides of the aminotriarylmethane dyes are colorless or light colored materials which show no pronounced change on exposure to light. However, in the presence of a suitable activator, these substances become sensitive to ultraviolet and respond to irradiation by the development of a pronounced color. The photoactivated cyanides are useful for actinometry of the ultraviolet, for measuring the output of germicidal and erythemal lamps, for measuring the strength and dosage of sunlight, and for photography by short wave length ultraviolet. They are also useful in receiving the tracing in recording instruments and for many other uses. In general, the

activated dye cyanides have maximum wave lenght limits of sensitivity ranging from a wave length of from about 3000 AD. to about 3650 A.U.

provide excellent photoactivators for dye cyanides for thepurposes enumerated above, and have numerous advantages over the activator materials previously known. Thus, activatorsfr om the amide class provide better solvents for difiicultly soluble dye cyanides than the previously, known photoactivators, and thereby make possible more concentrated and reactive photosensitive solutions v could be made with the previously knownmaterials. Itjis also possible to prepare supported photosensitive products having a greater proportion of activated dye by p izing the increased solvent power of the amide actors. sustantial-ly no odor and are essentiallyjneutral in reaction. Moreover, the amides are available over a wide range of vapor pressures so thatactivators for specific usages may be selected as desired. In addition to the pro vision of liquids of high solvent power, the amides provide a whole series of photoactivators with sulficiently high-melting points so that photosensitive systems solid at room temperature can be produced from them. Papers and other sheet materials sensitized with such solid systems'provide images that remain sharp and do not dif= fuse. The amides of the higher fatty acids such as stear The solid photosensitive of dye cyanides. However, such systems maybe utilized I It has now been found that the carboxylic acid The amides also have the advantage of having 2 cyanide of an aminotn'arylmethane dye activated an amide type of activator. it

Another object of the invention is to provide highly, concentrated and reactive photosensitive compositions and,

systems utilizing a solution of a dye cyanide in an amide activator.

A further object of the invention is to provide water: insoluble, solid, photosensitive materials and systems containing a dye cyanide and a solid amide activator therefor.

Another objectof the invention is to provide slow printing materials utilizing solid sensitizing systems.

A still further object of the invention is to provide a method for increasing the sensitivity of a slow printing material.

Amides suitable for use as photoactivators in accord ance with the present invention are the primary amides, the monoal'kyl amides, and the dial'kyl amides of the aliphatic carboxylic acids. These amides are represented by the formula RCONR R wherein R may be hydrogen or an aliphatic radical and R and R are hydrogen or alkyl radicals. Thus, the amides may be any of the series from fonnamide and its mono and disubstitutcd derivatives to the amides of the higher fatty acids and their mono and disubstituted derivatives. Examples are; formamide, methyl formamide, dimethyl formamide, diethyl formamide, acetamide, methyl acetamide, dimethyl acetamide, and diethyl acetamide, propionamide, n-butyr amide, n-valer amide, n-capro amide, and stearamide. Amides of the polycarboxylic acids may also be used.

, The aliphatic radicals of the compounds of these examples let Cyanide (4,424"-tris-dimethylamino-triphenylacetonitrile), Ethyl Violet Cyanide (4,4,4"-tiis-diethylaminotriphenylacetonitrile), and new Fuchsine Cyanide (4,4, 4-triamino-3,3',3"-trimethyltriphenylacetonitrile) r Examples of hydrophilic dye cyanides which are made. photo sensitive with amide activators are Formyl Violet Cyanide (the cyanide of the dye having Colour Index 698), Fast Acid Violet Cyanide (the cyanide of the dye having Colour Index 696), En'oglaucine Cyanide (thecyanide of the dye having Colour Index 671), Ethyl Green Cyanide (the cyanide of the dyehaving Colour Index 685 Xylene Blue A'S Cyanide (the cyanide ofthe dye having Colour Index 673), Aurin Cyanide (4,4',4"-trihydroxytriphenylacetonitrile), and Patent Blue V Cyanide (the cyanide of the dye having Colour Index 712). photoactivating property of the amides has been effective with all of the dye cyanidematerials tested, and appears to be general. However, since the hydrophilic dye cyanides are readily activated by water and hydrocolloids,

.the use of. the amides as activators is of greatest iml portance with the hydrophobic types. 'aniide yield photosensitive waxes which, unlike carbo advantageously with all types of dye cyanides. Slow printing materials as Well as fast printing materials may j be readily formed from the amide activated-dye-cyanide Accordingly, an object of the present invention is 6 systems.

provide novel photosensitive compositions comprising a As previously stated, the amides form good solvents and photoactivators for the difiicult soluble hydrophobic .dye cyanides.. .Those preferred for the violet dye cyajnidespcrysta'l violet cyanides and ethyl violet cyanides are the dialkyl carboxylic acid amides, e.g. dimethyl jHeretogfore, Malachite Green Cyanide in alcoholic solution has been preferred for use in actinometry. The

choice of Malachite Green Cyanide was predicated on Patented: May 10,1960,

The'

the fact that it is thirty times as soluble in alcohol as Crystal Violet Cyanide which otherwise would bepreferable because of the darker and stronger color which this dye yields on irradiation. (L. Harris and J. Kamin- A slow print paper was provided in Example 13 of U.S. patent, No. 2,676,887 by the addition of a screening dye to the sensitizer. The solid higher-molecular weight amide activators afford a means for attaining the same sky, J.A.C.S., v. 57, pages 1158-9; 1935.) Crystal Violet result without the use of a screening dye. Cyanide has been found, to be so soluble in the dialkyl It has also been found that materials incorporating carboxylic acid amides that actinometric solutions are dye cyanides with solid amide activators and having an now provided which are vastly superior to the Malachite initially low photosensitivity can be activated by a simple .Green Cyanide in alcoholic solution. Actinometric soluprocess to a much higher sensitivity. Such a material tions of Crystal Violet Cyanide in amide activators nearly 10 may be stored with fewer precautions to exclude radiathree times as concentrated as alcoholic Malachite Green, tion than an initially more sensitive material, and may Cyanide actinometric solutions can be prepared. These be handled under bright light conditions for placement solutions can be used satisfactorily in shorter absorption in a machine where the activation will take place just cells. Moreover, the amide solution of Crystal Violet before use. The slow printing materials are activated by Cyanide forms a stable color on irradiation and does not heat treatment at a temperature of about 100 to 110 require the addition of the hydrochloric acid generally C. for a short length of time. Long heating is not necesused to prevent fading of the color otherwise undergone sary for efiecting the increase in sensitivity. All that is byMalachite Green Cyanide solutions in the dark. The necessary is that the actual temperature of the paper or use of hydrochloric acid in quantitative work with dye other activated material be raised to 100 to 110 C. for cyanides is hazardous because more than a very small even a fraction of a second. Thus, the heat treatment amount reduces the photosensitivity of the solution and may be carried out as a continuous flash heating process; may change the absorption spectrum of the dye formed for example, wherein the activated material is passed in the photoreaction and thus lead to false results in its continuously between heating and cooling means, or may colorimetric determination. be carried out batchwise in a suitable oven.

The amide activators also provide improved photo- .The photosensitive compositions may be prepared by 't'ropic'solutions. While the measurement of total radiant dissolving the dye cyanide in the amide at room tempera-f energy requires an irreversible photochemical reaction, ture if the amide used is liquid at this temperature, or the thedirect measurement of radiant intensity requires a liquid amide may be slightly warmed to speed solution, reversible or phototropic reaction, such as was employed e.g. to about 100 C. When solid amides are used, they by Frankenburger, Robl and Zimmermann, US. Patent may be heated to a few degrees above their melting point, No. 1,845,835. The patentees utilized alcoholic soluand the dye cyanide then mixed into the'molten mass. tions of Malachite Green Cyanide. Solutions of this The-components may also be combined and applied in dye cyanide in an amide such as diethyl-acetamide may a common volatile solvent that is laterevaporated. be prepared which are nearly twice as concentrated as The application of the photosensitive composition to the previously known alcoholic solutions and therefore base materials is similar to that described in my aforeproduce a stronger reaction or may be used in thinner mentioned patent, 2,676,887. Thus, the liquid or molten layers and smaller apparatus. The activating solvent mixturesmay be used to impregnate filter papers, or may has a relatively low vapor pressure and does not evapbe applied as'a coating or film to other base materials. orate like the alcohol from an alcoholic solution. Most The paper used as a support for the activated dye cyaimportantly, the dark reaction is much faster than in a nide materials should be free from drying oils and resins. pure alcoholic solution of Malachite Green Cyanide and The paper stock used for photographic developing paper therefore the addition of potassium cyanideor hydroxide is satisfactory, as are the Waterleaf papers such as filter is not necessary to bring about the attainment of equipapers. Sized papers which are free of rosin or drying librium within a reasonable time. 7 oils and other auto-oxidizing substances are also satis- The excellent solvent power of the amides has also factory. The photosensitive compositions may be supbeen foundto be useful with the relatively difiicultly soluported directly on the paper or on glassor on other base ble cyanides of the red aminotriarylmethane dyes, eg materials. They may also be combined with other mateiRosaniline, Pararosaniline and New Fuchsine. With the rials to modify the action of the ultraviolet radiation. cyanides of the red dyes, the primary, monoalkyl and The proportions of dye cyanide and amide activator are jdialkyl carboxylic acid amides are very efiective, these not critical and can be varied over a wide range. V dyes being readily soluble in all three types of amides. A great number of combinations of the dye cyanides V ,Relatively fast-printing materials are provided by dye and carboxylic acidfarnides have been prepared and cyanide compositions activated with the amides oflower examined. All that have been prepared have proved to molecular weight. Materials that print more slowly are be photosensitive at room temperature whether the final useful in the actinometry of intense light sources, or to product was liquid or solid. The following table profollow the course of other slow photochemical reactions. vides numerous examples of the dye cyanide amide- Cyanlde ot- Amlde Mala- Un- Parachlte Seto Crystal identirosan- Rosan- New Green glauclne Violet fied iline iline Fuchslne 1 Violet;

Formamlde X x x x x x x Methyl formamide.-. X X X X X X X Dimethyl formamirln X X X Dlethyl formamide X 1 X X X X X Acetamide X X X Methyl acetamide:

liquid X X X X X X X solid X1 X X X Dirnethyl acetamide- X X X X X X X Diethyl acetamide- X X X X X X X Propionamide X X X X X n-Butyra e.- X X X X X n-Valer amide..- X X X X X n-Capro amlde X X X X X Btear m X X 5 activated" compositions prepared. In each instance, the dye cyanide was incorporated in the liquid ormolten amide, and was applied to a paper base. In the table, the designation X indicates that the composition has been made and examined, and found photosensitive. If a combination had been made and found to be insensitive to ultraviolet, a designation 1 would have been placed in the table. No such combinations have been found.

The invention will be further illustrated by the followingexamples of practice:

Example I A solution is made of 5 grams of pararosaniline cyanide in 50 ml. of toluene, 50 ml. of acetonitrile and 1 ml. N-methylacetamide- (measured at 30 C.). Twenty pound water leaf paper is impregnated with this solution, and the toluene and acetonitrile evaporated in dry' air. The resulting sensitized p aper is stored in closed containers. The paper prints out a red image on exposure toultraviolet of wave lengths shorter-than 3 300 A., and is more sensitive and prints faster than previous pararosaniline cyanide sensitized materials, such as the paper described in Example 11 of US. Patent No. 2,676,887.

Example 2 Another paper that prints faster than previous dye cyanide sensitized materials is prepared as follows: 1 g. of rosaniline cyanide is dissolved at 50 C. in 100 ml. of formamide, the solution diluted with an equal volume of methyl alcohol and used to impregnate water leaf paper, which is air dried to the removal of the methyl alcohol, The paper is strongly photosensitive.

Example 3 Three g. of crystal violet cyanide is dissolved in 1 liter of dimethylformamide at 50 C. and the resulting clear solution stored in a brown bottle. The solution is stable and no crystallization takes place on. long storage at 20 C. This solution has many advantages for actionometry over the alcoholic solution of malachite green in alcohol previously recommended.

Example 4 A fast reacting phototropic solution is prepared by dissolving 2 grams of Malachite Green Cyanide in 100 ml. of diethylacetarnide at about 50 C. This solution may be used for direct measurement of radiant intensity and requires no additional reagents to bring about the attainment of equilibrium within a reasonable time.

Example 5 Paper is impregnated with a solution of 2 g. of setoglaucine cyanide (the cyanide of the dye having Colour Index 658), prepared as described in Example 4 of my copending application Serial Number 551,982 (now abandoned in favor of continuation-impart application Serial No. 650,085, which matured into Patent No. 2,877,166, granted March 10, 1959) in 100 ml. of dimethylacetamide and 500 ml. of acetonitrile, and air dried to the complete removal of the acetonitrile. The sensitized paper is stored in closed containers. On exposure to ultraviolet of wave length shorter than about 3400 A. the paper prints a permanent blue image.

Example 6 A slow printing material is prepared as follows:

One g. of new fuchsine cyanide, the prepared by reacting New Fuchsine, Color Index 678, with sodium cyanide is dissolved at 110 C. in 100 g. of stcaramide and 30 g. of diethylacetamide. Water leaf paper is impregnated with this solution at 100 to 110, and then cooled. On exposure to ultraviolet the impregnated paper slowly prints out a deep red image. The printing is slow enough to use in the dosimetry of therapeutic ultraviolet and for sunburn meters to be worn outdoors or at the beach.

Example 7 A slow printing material which may be activated to higher sensitivity is prepared as follows:

Paper is impregnated with a solution of 2 g. of new fuchsine cyanide and g. of hexanamide in 200 ml. of acetonitrile and 400 ml. of toluene at 45 C. The coated paper is air dried to the elimination of the acetonitrile and toluene. So dried, the paper prints a little more slowly than the paper described in Example 6, and does not give as deeply colored an image on long exposure. The hexanamide paper is now heated for 5 minutes in a C. oven and cooled, and the printing speed is increased more than 60 fold.

I claim:

1. A photosensitive composition comprising anintimate admixture of an aminotriarylmethane dye cyanide with an aliphatic carboxylic acid amide activator.

2. A photosensitive composition comprising an intimate admixture of an aminotriarylmethane dye cyanide with a carboxylic acid, amide activator having the following formula:

R1 R-CON'/ R: wherein R is selected from the group consisting of hydrogen and an aliphatic radical and R and R are selected from the group consisting of hydrogen and an alkyl radical.

3. A solid photosensitive composition comprising an intimate admixture of a cyanide of a Rosaniline dye and steararnide.

4. A photosensitive product comprising a supporting base carrying a photosensitive composition comprising an intimate admixture of an aminotriarylmethane dye cyanide with an aliphatic carhoxylic acidamide activator having the following formula: 1

R: wherein R is selected from the group consisting of hydrogen and a saturated aliphatic radical and R and R are selected from the group consisting of hydrogen and an alkyl radical of 1 to 2 carbon atoms.

5. A photosensitive product comprising a paper impregnated with a solution of an aminotriarylmethane dye cyanide in an aliphatic carboxylic acid amide having the following formula:

R1 R-OON/ R: wherein R is selected from the group consisting of hydrogen and a saturated aliphatic radical and R and R are selected from the group consisting of hydrogen and an alkyl radical of 1 to 2 carbon atoms.

6. A photosensitive product comprising a supporting base carrying a photosensitive composition consisting of an intimate admixture of an aminotriarylmethane dye cyanide and a solid, Water-insoluble, aliphatic carboxylic acid amide having the following formula:

R-C ON R: wherein R is selected from the group consisting of hydrogen and a saturated aliphatic radical and R and R are selected from the group consisting of hydrogen and an alkyl radical of 1 to 2 carbon atoms.

7. A photochemical process comprising the steps of photoactivating an aminotriarylmethane dye cyanide with an aliphatic carboxylic acid amide and irradiating said 7 wherein R is selected from the group consisting of hydrogen and a saturated aliphatic radical and R and R are selected from the group consisting of hydrogen and an alkyl radical of 1 to 2 carbon atoms. 8. The method of increasing the sensitivity of a printing material sensitized with an hydrophobic aminotriphenylmethane dye cyanide and a non-volatile aliphatic carboxylic acid amide activator having the following formula: V

B-CON wherein R is selected from the group consisting of hydrogen and a saturated aliphatic radical and R and R are selected from the group consisting of hydrogen and an alkyl radical of 1 to 2 carbon atoms, comprising: heating said sensitized material to a temperature within the range of from about 100 to 110 C. and coolingit again to room temperature prior to exposure.

' 9. The'method of claim 8 wherein said dye cyanide is the cyanide of the dye having Colour Index 678 and said amide activator is hexanamide.

10. A slow-printing material adapted to be activated 'to high sensitivity by heating followed by cooling, comprising: a supporting base carrying a photosensitive composition including an intimate admixture of the cyanide of the dye having Colour Index 678 and hexanamide.

11.A' fast reacting phototropic solution comprising a 'solution of 4,4'-bis-dimethylamino-triphenylacetonitrile in diethylacetamide.

12. A photosensitive composition comprising an int:- mateadmixture' of an aminotriarylmethane dye cyanide with acarboxyl ic acid amide activator having the folloW- ing formula: 1 i

R1 a-ooN wherein .R is selected from the group consisting of hydrogen anda saturated aliphatic radical and R .and R are selected from the group consisting of hydrogen and an alkyl radical of one to two carbon atoms.

13. The photosensitive composition of claim 1 wherein the carboxylic acid amide activator is a primary amide. '14. The photosensitive composition of claim 1, wherein .the carboxylic acid amide activator is a mono-alkyl amide.

' 15 The photosensitive composition of claim 1 wherein the carboxylic acid amide activator is a dialkyl amide. j. 16. The photosensitive composition of claim 1 wherein the dye cyanide is in solution in the carboxylic acidamide activator.

- 17. The photosensitive composition of claim 1 wherein the carboxylic acid amide activator is a solid, waterinsoluble compound.

18. The photosensitive composition of claim 1 wherein the dye' cyanide is of the hydrophobic type and said hydrophobic dye cyanide is in solution in a dialkyl aliphatic carboxylic acid amide activator.

19. The photosensitive composition of claim 1 wherein the dye cyanide is 4,4',4"-tris-dimethylamino-triphenylacetonitrile and said dye cyanide is in solution in a dialkyl aliphatic carboxylic acid amide activator.

Kirby Mar. 2, 1943 Chalkley Nov. 7, 1950 

1. A PHOTOSENSITIVE COMPOSITION COMPRISING AN INTIMATE ADMIXTURE OF AN AMINOTRIARYLMETHANE DYE CYANIDE WITH AN ALIPHATIC CARBOXYLIC ACID AMIDE ACTIVATOR. 